This car is too simple, I can't make it work.

So, word got around that I have odd cars (ie, not a Big 3 pickup) and a Mk2 Sprite wandered into my garage. It has a freshly built 1275 with a new DCOE but the owner has never managed to get it running.

I am now 75% better than him. I have three happy and running cylinders, but I can't seem to get #4 to wake up at all. It's got spark. #3 is running.

So. I've checked all the jets in the carb, they seem to be clear. There was some nasty looking gas in the carb when I got the car but it's been replaced with fresh dinosaurs. I even swapped the main jets around, but no change. The plug is dry, as best as I can tell.

What I can't figure is how I can have just one dead cylinder instead of two. I'd be looking at injectors if it was fuel injected, but these weird toilet bowl things full of gasoline are too hard

Suggestions?

Swap with LS1? I heard that is popular with other small cars....

In all serious I have not idea, my only carbed car was a fiat x1/9, I only ever looked in the engine bay, never played with anything tuning related.

stuck valve? idunno. how long was it sitting?

I got a 45dcoe lying around, worked on my mini before it at a valve, if you want to try a spare. I also have a set of pistons and rods if you ever want to make it a 1380.

Do a compression test across the motor, see what the "happy" jugs are doing as well as the dead.

Broken Intake Rocker on dead cylinder.

I think Dave has the answer...

That will often be accompanied by heavy oil consumption as well.

Yeah, stuck valve or rocker arm (or valve way out of adjustment). Look for intake manifold leak too (spray WD-40 near it while it's idling). And see if one stud on distributor cap is bad or there's a carbon crack near it that is bleeding off some of the current. And try swapping a plug from a "good" cylinder just in case you have a bad one. If those aren't it, it's time for a compression test or leak-down test.

The gas may be crappy, but if three are running, it can't be that bad.

I've have several Spridgets running on one carb (instead of both) where the farthest cylinder will barely run. Actually, my brother's Midget is like that right now.

Not sure about Webers. My MGB came with one (DGV) and I just bought two HS4 SUs to return it to the "proper" setup.

valve isn't opening

I can't beliveve that HE is asking us for help!!!! But, this is an absolute fountain of information. Hope you get it fixed, oh God of all Miatas.

Oh yeah, could be a wiped-out cam lobe too, but if it's a recent rebuilt, that seems unlikely. Headgaskets are not uncommon, but it's usually between #2 and #3

Hey, it's how you learn! I should point out this is not my car, the owner asked me to bring it to life for him.

I just tried a compression test. Given that it's a freshly built motor from a shop that I usually trust, I was assuming that everything inside was good. Ummm, no. No compression at all on #4, and not a whole lot on #2 either. So, valve adjustment time it is. I'd already pulled the valve cover off earlier to make sure that there were no broken rockers, for example. But I guess this particular step in assembly never happened.

It's always fun working on a car like this. Everything is distilled down to fundamental principles.

More than 0.032" of clearance on the exhaust (spec is 0.012") and no clearance on the intake on #4. Hmm, might have been part of the problem.

With all 8 valves adjusted it - they all needed it - you can even hear a difference in how the car cranks. It runs pretty happily now. Thanks for pointing out the obvious to me, folks. I'm too used to hydraulic lifters, even though the Mini and Rover have the same sort of setup.

Bmc engines just love valve adjustments

mmm-mmm. Now you got the angry sewing machine sound, right?

pres589 wrote: see what the "happy" jugs are doing

Heh-heh-heh...

You said "happy" jugs.

In the next 1000 mies or so, the engine will probably benefit from a couple of head re-torques and valve adjustments.

A fresh 1275, with a Weber -- you could always offer to break it in for your friend

Definitely not - this car is still a way from being done. I pulled a wheel off when trying to find out why the car wouldn't push easily, and the rear drums are full of grease. Half the wiring isn't hooked up, the only functional gauge is oil pressure and the owner claims there are no pads in the front brakes. There's no exhaust past the LCB header. Etc, etc.

My job was just to get it up and running. Mission accomplished. He's going to take care of the rest. Hopefully I'll see the car at one of our local autocrosses again soon. I'll mention the need for the head retorques and the valve adjustment down the road. He's owned this car for a long time so hopefully he's aware of this. He'd made the same assumption I did, that the shop that was paid to build the engine would have adjusted the valves.

Now it's time to get back to work on my own critters. The Targa car has to get ready for the trip to the Mitty, and the MG is still waiting for the Big Transplant...

^^garage of sexiness FTW

Never ASSUME Make me wonder at the quality of the rebuild.

Keith, what is the car in the far back of the garage? I can figure the rest of them out

InigoMontoya wrote: Keith, what is the car in the far back of the garage? I can figure the rest of them out

Looks like the MGBGT awaiting the LS1 swap

Damn, I gotta get a better puter. The farthest back I can see is the vry ass of the mini.

Porksboy, you don't need a better computer, you need a better browser. Go get yourself Firefox, Safari or Chrome. You'll be glad you did.